1. Field of the Invention
This invention refers generally to an improvement in the refrigeration process and more particularly to a higher efficiency refrigeration process which is enhanced by the inclusion therein of an expander-compressor transducer. In addition to refrigeration, the process is applicable to air conditioning, cryogenic equipment, and heat pumping systems.
2. Description of Prior Art
In the past, the basic components of the well-known refrigeration or vapor compression systems included a compressor, a condenser, a throttling expansion valve, and an evaporator. The compressor is generally driven by some outside motive source such as an electric motor, engine, or turbine and compresses the cold-refrigerant vapor exiting from the evaporator to a high pressure and temperature. This vapor is generally superheated, high-temperature, high-pressure gas and flows into the condenser where such gas is condensed to a compressed liquid state. This liquid then passes through a throttling expansion valve from which the liquid passes from its inflowing high-pressure, compressed-liquid state to a cooled outflowing low pressure, as a very wet vapor, consisting of a mixture of liquid and vapor under saturated conditions of temperature and pressure. This process is variously known as throttling, is enthalpic or irreversible, free expansion, which is wasteful of energy and is characterized by a restriction between the condenser and the evaporator. The restriction is an orifice, a capillary tube, or a valve. The cooled, low-pressure wet mixture flows through the evaporator, where heat is absorbed from the surrounding environment, and in so doing, changes in state from an initially wet mixture to a saturated or slightly superheated vapor on exiting from the evaporator. The cooling effect is brought about by the change in state of the liquid particles to a vapor and is known as heat of vaporization. The cool, low-pressure vapor is drawn into the suction side of the compressor and repeats the cycle. Similar thermodynamic processes employing the above described vapor compression system are used in air conditioning, cryogenic equipment, heat pumps and refrigerators. The conventional systems are in wide use but have performance limitations primarily attributable to the described throttling process. Conventional vapor compression systems degrade rapidly in performance as the temperature differential increases between the low-temperature evaporator and the high-temperature condenser. This temperature differential is inherent in the particular application and reflects the spread between the ambient temperature and operational temperature required by the system. Frequently, as in the case of air conditioners and heat pumps, poor performance is experienced under high-ambient temperatures. In ultra-low-temperature systems, such as cryogenic equipment or low-temperature refrigerators, generally two or more stages of vapor compression refrigeration are utilized to obtain satisfactory operation over a broad temperature spread. In the above described vapor compression cycle, increasing inefficiency is a concomitant of increasing temperature spread. Such a relationship between temperature spread and efficiency is thermodynamically demonstrable even for the most efficient refrigeration or heat pumps known, including the reverse Carnot cycle.
In closely examining the thermodynamic properties of the vapor compression cycle just described, the conclusion was drawn that, while conventional throttling mechanisms are in technological terms simple devices, those devices commonly employed waste energy and restrict the performance of the overall cycle because of thermodynamic irreversibility.
The solution of this problem, not shown in the prior art, would be the replacement of the conventional irreversible expansion process. Additionally, the solution would optimally include utilizing the work obtained from the reversible expansion to precompress partially the refrigerant vapor, thereby resulting in obtaining a greater amount of refrigerating capacity together with reduced net compressor work. Such an improvement would not only yield more efficient performance under standard conditions, but would also extend the useful temperature range of vapor compression cycle beyond the presently realized vapor compression range.
By the way of background, in the prior applications indicated above numerous patents have been provided as references or have otherwise been considered as of interest in preparing this application, and those which bear filing dates prior to the filing of the parent application are the following:
______________________________________ Patent No. Inventor ______________________________________ 3,613,387 S.C. Collins 3,591,317 G.D. James 3,413,815 E.G.U. Granryd 3,301,471 M.E. Clarke 3,234,738 W.L. Cook 2,519,010 E.W. Zearfoss, Jr. 2,494,120 B.J. Ferro, Jr. 1,693,863 T.I. Potter 1,486,486 P.W. Gates 1,245,603 W. Lewis 801,612 W. Schramm 283,925 J.B. Root ______________________________________
The prior art devices do not provide the previously detailed efficiency advantages, nor do the patents describing such devices reach toward the present invention in which a unique, thermodynamically regenerative device provides cooling which said device simultaneously provides work output to a piston.